Sequoia scientists recently attended the fourth International Ocean Colour Science (IOCS) meeting and NASA Ocean Color Research Team (OCRT) meeting during the week of 8 April 2019 in Busan, South Korea. The IOCS meeting is organized by the International Ocean Colour Coordinating Group (IOCCG) in partnership with the Korea Institute of Ocean Science & Technology (KIOST), NASA, EUMETSAT and Airbus. The purpose of the meetings is to bring together the ocean color community to provide updates on missions and projects, share data and ideas, and foster collaboration among scientists and agencies.

Current Sequoia LISST technology is used in studies linking ocean color, particle size, and biogeochemistry. Sessions with potential application for Sequoia’s particle measurement technologies included Requirements for Phytoplankton Characterisation, High Temporal Resolution Applications, and Remote Sensing of Optically-Complex and Shallow Water.

Particle size distribution measurements from LISST laser diffraction instruments and particle images from the LISST-Holo2 submersible holographic particle imaging system are useful tools for characterizing particles in situ, including phytoplankton. These same instruments can be used to better understand how changes in the characteristics of suspended particles affect the in-water optical properties, and ultimately the ocean color remote sensing signal, especially in optically-complex coastal waters.

For high-resolution studies of in-water particle optical properties, LISST sensors provide a means to measure size distribution in moored, towed, and underway systems. For longer-term underway deployments the FlowControl valve system can be used to automate clean water blanks and produce calibration and fouling drift-independent particle measurements, for LISST instruments as well as other flow-through instruments such as the SeaBird Scientific (WET Labs) ac-s spectrophotometer. The new LISST-Horizon system is designed for deployments in shipboard underway flow-through systems and combines LISST laser diffraction technology, automated clean water blanks, and adds side scattering measurements for extending the particle size range and calculating additional in-water optical properties.

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Sequoia scientist Dr. Wayne Slade participated in the session Emerging New Technologies for Ocean Colour Research, presenting ongoing R&D efforts at Sequoia to build a hyperspectral backscattering instrument “HYPERBB”, and an overview of the LISST-VSF instrument for measuring the volume scattering function. Hyperspectral backscattering has been identified as a measurement gap in closure and validation studies for planned hyperspectral ocean color sensors; and both higher spectral resolution backscattering and angular volume scattering function measurements can be used to help characterize particles. The LISST-VSF is a product available for sale today and the HYPERBB is scheduled for release in Q1 of 2020. Sequoia scientist emeritus Dr. Curt Mobley, well known for his HydroLight radiative transfer numerical model software commonly used in ocean color remote sensing work, presented the final keynote of the week-long meeting on “The evolution of ocean radiative transfer modeling.”